RFR: 8294983: SSLEngine throws ClassCastException during handshake [v3]

[Kevin Driver]

> Fixes a scenario where a `ServerHandshakeContext` might be cast as a `ClientHandshakeContext`.

Kevin Driver has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:

 - address code review comment
 - updated copyright
 - set consumer to null if we're not in client mode

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Changes: https://git.openjdk.org/jdk/pull/13727/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13727&range=02
  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/13727.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13727/head:pull/13727

PR: https://git.openjdk.org/jdk/pull/13727